Protective coating



itself. 2

Patented Aug 6 19.40

UNITED STATES PATENJ orF cE 2,210,167 rao'rncn'va' con'rmc Paul W. Felt, Minneapolis,

assignor to Brown & 'Bigelow, St. Paul, Minn., a corporation of Minnesota No Drawing. Application December Serial No. 177,789

' 8 Claims.

Because of the common practice of printing upon the barrels of pencils andthe like, many attempts have been'made to provide a protective coatingfor the printing which will prevent the printing or the designs formed on the barrel from being rubbed off.

It is of course, possible to emboss printing or designs on barrels of this type, but this process. is costly and slow commercially, Attempts have accordingly been made to coat the pencil with a coating of lacquer or the like. However, nitrocellulose. lacquer hasa greater aflinity for' the plasticizer used in the formation of the cellulose acetate articles, than'has the body of the article Accordingly, when the cellulose acetate body is coated with nitrocellulose lacquer, a inigration of the plasticizer from the pencil body to the lacquer takes place; This action is greatly hastened by high temperatures and humidity. Accordingly, when pencils having bodies formed of cellulose acetate. and coatedwith nitrocellulose lacquer are carried in the pocket on a hot day, the plasticizer soon migrates into the lacquer, softening the lacquer and making the lacquer film extremely tacky.

Attempts have also been made to coat cellulose acetate bodies with resinous lacquers, but it has been found thatwhile many of such lacquers do not have the aflinity for the plasticizer of nitro-' cellulose lacquer, these materials do act to draw the plasticizer from the cellulose acetate body,

causing this plasticizer to be interposed between the coating and the body and printing orapplied design may be observed. 'I'he success of my invention relies upon the selection of a suitable combination of solvent and 55 causing the coating to lose its adhesive qualities. In such cases, the coating will peel body.

The object of the present invention is to provide a protective covering by coating the cellulose acetate body of the article with cellulose acetate. 0bviously, such'material when applied will form an integral part of the body, but will act as a transparent film through which the diluents which will cut the raw cellulose acetate,

off or slip off from the article but'will not attack the cellulose acetate body to be coated.

It is a well known'fact thatcellulose acetatelacquers comprised of such solvents as acetone, methyl ethyl ketone, ethyl lactate, or any other 1 of the active cellulose acetate solvents, will cause a wrinklingor distortion of the surface of a molded cellulose acetate article. However, these same-solvents in combination with the proper type of diluent can be adjusted so as to still be solvents for] raw cellulose acetate, but will not attack the surface of the molded cellulose acetate 7 article.

The alcohols and the aromatic hydrocarbons are the most popular diluents in cellulose acetate lacquers. The type of raw cellulose acetate used determines which of these two diluents shall be used.- More alcohol or less toluol (being representative of aromatic hydrocarbons) may be used as a diluentin a solution containing low acetyl content cellulose acetate, than in a solution with either medium or high acetyl content cellulose acetate. The medium acetyl type will,

however, have the greatest tolerance for a mix,

ture of alcohol and 50% toluol."

It has been found that not a sufllcient amount of these two diluents can beadded to the cellulose acetate lacquer to tone down the active solvents so that they will not' attack the surface of the cellulose acetate molded'article, but I have now i discovered that in the presence of these two diluents, either separatelyor in combination with one another, depending upon the raw cellulose acetate, other diluents, which when used alone would be tolerated'only in very small percentages in the lacquer, can be added in large enough quantities to tone down the most active solvents of cellulose acetate. Among these diluents I list the following, but do not wish to limit myself to these alone as there are no doubt others in the same groups which will give equally good results. First there are the esters such as butyl acetate or isopropyl acetate. Then there are the ketones such as dipropyl ketone or methyl isobutyl ketone. Also, the alcohol-ethers, such as ethylene glycol 'monoethyl ether, or ethylene glycol monobutyl ether. There are also the lactates, such as butyl lactate. all ofthese mentioned diluents are either nonsolvents or have only a slight solvent action on cellulose acetate, and if used alone, would not be tolerated to any extent in a cellulose acetate lacquer; but, in combination with alcohol, aromatic hydrocarbons, or mixtures of both as much as 50% maybe added without causing the cellu- As will be noted,

. certain materials are advantageous.

diluents may be used with any solvent combination, the weaker the active solvent, the smaller the percentage of diluent required.

As in the case of diluents previously described, there are a great number of plasticizers which may be used for my purpose. Accordingly, it is not the purpose of this'invention to limit the scope of the patent to one specific type of plasticizer. Also, just as in the case of diluents, It is be-.

lieved preferable, however, to use a plasticizer which is not a solvent for cellulose acetate, but

which is compatible therewith; For example,

dibutyl phthalate or tricresyl phosphate may be used. There are also a great number of plasticizers produced commercially under various trade names which will provide good results. For

some uses it is not even necessary to incorporate a plasticizer in the lacquer, as sufficient plasticizer is obtained by transmission from the article upon which the film is applied.

It is not necessary to limit the present invention to the use of straight cellulose acetate lacquers since there are various natural and syn-' thetic resins compatible with cellulose acetate which might be substituted for a part of the acetate without materially changing the properties of the lacquer film. Among the natural resins suitable for use are gum accroid andgum guaiac.

4 Because of their color the uses of these resins are limited in coating lacquers. Among the synthetic resins which may be used may be found a great number on the market under various trade names which in combination with cellulose acetate produce some very nice finishes. These resins may produce either a color or colorless coating accord ing to the resin used.

The following formulas disclose in general the formula for my coating:

Parts Active solvent 40-80 Diluent 15-50 Plasticizern 0- 5 Cellulose acetate 1-15 A secondgeneral formula may be as follows:

Active solvent parts 40- 80 Dlluent do 15- Dibutyl phthalate do 0- 5 Cellulose acetate do 1- 15 Resin (synthetic or natural) per cent of the totalsolids" 0-100 As specific examples of coatings which could be produced under these general formulas, the following more specific formulas are-quoted. It will be understood that other diluents, active solvents,

and plasticizers maybe used in place of the one specifically mentioned, but those cited in the formula are believed extremely suitable for the purpose.

Parts (Active solvent) Ethyl acetate 50 Ethyl alcohol 5 Butyl acetate 35 Solids Cellulose acetate 10 1r. (Activesolvents).. Ethyl acetate 40 Ethyl alcohol 10 laments-mi Butyl acetate .40

- Cellulose acetate 7 solids. Resin 3 .off.

2,210,167 lose acetate to come out: This combination of Printing or designs placed upon bodies of cellulose acetate may becovered by coatings in ac-- cordance with the foregoing formulas in such a manner that the printing will be embedded within the body of the article as the coating forms in reality an integral part of the body. Pencil barrels for example, formed of cellulose acetate can be printed in the. usual manner, and this printing protected by embedding the same within the body where it is visible through the transparent film, but where it is, not accessible and cannot be rubbed I have found a solvent when used in combination with raw cellulose acetate with or without diluents forms a lacquer which will not attack the articles to be coated enough to cause any noticeable surface distortion or wrinkling. This solvent is ethylene glycol mono-ethyl-ether mono-acetate, which is better known as cellosolve acetate or betaethoxyethyl acetate, and has the formula CzHsOCHzCHzCOzCI-Ia. This solvent has a rather high boiling point range (14 5 to 166 C.) and a vaporpressure of about 3 mm. at 30 C. This feature is desirable as it gives the lacquer good flowing properties and practically eliminates all chance for blushing since water is but slightly soluble in it. Its evaporation rate is not so low that the setting of the lacquer film is unduly retarded. Cellosolve acetate is also a good solvent for resins and has, the property of imparting a .high gloss to lacquer films. 'Thissolvent may be used with any viscosity cellulose acetate, but for application by spray or by dipping as low a viscosity aspossible is desired. I

Cellosolve acetate may be used merely with the cellulose acetate, but for ordinary purposes it is common practice to use a diluent or a plasticizer or both in the formula. The formula may or may not contain a synthetic or natural resin.

As examples of the use of cellosolve acetate, in general, the following formula may beused:

Cellosolve acetate parts 80-100 Diluent 'do 0- l5 Plastlcizer ..-do 0- 5 Cellulose acetate do 1- 15 Resin (synthetic or natural) r of the total solids-.." 0-100 The following specific examples are typical of l the use of cellosolve acetate. It will be understood that other diluents and plasticizers may be used in the place of those mentioned:

, Parts Cellosolve acetate. 100 Cellulose aceta I '7 Cellosolve acetate Butyl acetate- 5 Cellulose aceta diluent, 15 to 50 parts;

deposited from .a ,mixture of active solvent for cellulose acetate, 40' to 80 parts; plasticizer, 0 to parts; cellulose acetate, 1 to par'ts;.and a said diluent comprising alcohol and another diluent material substantially non-solvent of cellulose acetate.

comprising in combination, an aromatic hydrocarbon, and v another diluent, material substantially non-solvent of cellulose acetate.

, 3 Cellosolve acetate- 92 4. An article or manufacture comprising sub- Butt'l acetate 5 stantially a molded body of cellulose acetate Dibutyl phthalate.. 3 having a coating thereupon, the coating beings Cellulose aceta I .7 deposited from a mixture of active tsolventofzz 5 a 7 cellulose acetate, 0 to 80 parts; plus i er,

g gggfi ggggfizli '5 parts; cellulose acetate, 1 to 15 parts and a V 7 diluent, 15 to 50parts; said diluent comprising Cellulose acetate g an aromatic hydrocarbon and another diluent Cellosolve acetatematerial ubstantially non-solvent of cellulose Cellulose aceta I 7 acetate. g Resin 5. An article of manufacture comprising sub- 1 Cellosolve acetate ---s----- 9 stantially a molded body of cellulose ace a Bu yi e te 5 having a coating thereupon, the coating being Cellulose aceta 7 deposited from a mixture 01' active solvent for Resin cellulose acetate, 40 to so parts; lglaszirti'iner, i; to g 5 parts; cellulose acetate,- 1 t0 P n 8 gfi gfigg gff 5 diluent, 15 to 50 parts; said diluent comp flnt mbutyl phthalate 3 a combination of alcohol with an a o a y ro- Cellulose acetate 7 carbon and another diluent material sub- Resin 7. stantially non-solvent of cellulose acetate.

, 6. An article of manufacture comprising subcenoselve acct? Y 97 stantially a molded body of cellulose acetate Dibutyl phthalate 3 having a coatingthereupon, the coating being Cellulose acetateee 7 deposited from a mixture of active solvent for Resin 7 cellulose acetate, 40to so parts; plasticizer, c to P In accordance with the patent te I have 5 parts: cellulose acetate, 1 to 15 parts; resin,

described the Principles o t u t of my from 0 part to an amount equal to the total I i and While I e fi fleav Set forth solids; and diluent, 15 to 50 parts; said diluent h best embodiment h r f, '1 wir to v comprising in combination, alcohol and another it nd r o h v us anges may be made diluent material substantially non-solvent 0! within the scope of the following claims withllulo ac tate, out d p ing from the spirit of my inv n n 7. An article of manufacture comprising sub- I claim: Y stantially a molded body of cellulose acetate 1., An r l of manufacture comprising 1 having .a coating thereupon, .the coating being nfia y a molded body of cellulose acetate, deposited irom a mixture of active solvent for avi a oa he eupo e said o t cellulose acetate, to to on parts; plasticizer, c to being deposited from a mixtureof ethyl-acetate 5 parts cellulose acetate; 1 'to 15 parts; resin, -5 Pa ethyl fl cfl i P b l' from 0 part to an amount equal to the total l ho 2- P p st iz r. parts; nd solids, and diluent, 15 to 50 parts; said diluent 40 cellulose; acetate, 7- 0 pa tscomprising in combination, alcohol, 'an aromatic 2. Anarticle of manufacture comprising subhydrocarbon, and another-diluent material substantially a molded body of cellulose acetate stantially non-solvent of cellulose acetate. having a coating thereupon, the said coating 8, Arfarticle of manufacture comprising subbeing deposited from a mixture of ethyl acetate; stantially a molded body of cellulose acetate 40-50 parts; ethyl alcohol 5-l0 parts; butyl having a coating thereupomthe coatingebeing alcohoL. 32-40 parts; tributyl phosphate, 0-3 deposited from a mixture of active solvent for parts, and cellulose acetate 7-10 parts. celiuloseacetate, 40 to 80 parts; plasticizer, 0 to 3. An article of manufacture comprising sub- 5 parts; cellulose acetate, V1 to, 15 parts; resin, stantially a molded body of cellulose acetate from 0 part to an amount equal "to the total havinga coating thereupon, the coating being solids, and diluent, 15 to 50 parts; said diluent Pam-w. m'rc u f 

